Split gate valve

ABSTRACT

Provided in some embodiments is a system that includes a split gate valve including first and second gate sections coupled together and configured to move together within a cavity of the split gate valve between an open position and a closed position. The split gate valve includes a rolling actuator to reduce friction and to convert a rotational input into a linear motion to move the first and second gate sections between the open and closed positions. In other embodiments is provided a method that includes converting a rotational input into a linear motion to activate a split gate valve via a rolling actuator. The method also includes seating first and second gate sections of the split gate valve against opposite first and second seats to provide a double seal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and benefit of U.S. Non-Provisionalapplication Ser. No. 13/083,384 entitled “Split Gate Valve”, filed onApr. 8, 2011, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to gate valves. More particularly, the presentinvention relates to a split gate valve employing a rolling actuator.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Gate valves are used in a wide variety of industries including oil andgas, power generation, food and beverage, water treatment, and the like.Gate valves include a gate that moves between an open and closedposition to control the flow of fluid through the gate valve. Gatevalves designed with large bores (e.g., approximately 5 inches orgreater) and/or for operating under higher pressures (e.g.,approximately 10,000 psi or greater) generally only include a singlegate (e.g., a slab gate) to seal a single side of a passage through thegate valve. These large bore and/or high pressure gate valves presentdifficulties and additional test time in testing the seal since bothsides of the gate valve need to be tested. Hence, there is a need toseal both sides of the gate valve, but designing the large bore and/orhigh pressure gate valve to seal both sides of the passage through thegate valve would require very high turning force to mechanically openand close the gate valve.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present invention willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is an exemplary schematic diagram of an embodiment of a splitgate valve having a rolling actuator;

FIG. 2 is a schematic diagram of another embodiment of the split gatevalve having the rolling actuator;

FIG. 3 is a schematic diagram of an embodiment of the split gate valvehaving the rolling actuator disposed within a cavity of the split gatevalve;

FIG. 4 is a schematic diagram of an embodiment of the split gate valvehaving the rolling actuator disposed between a pair of gate sectionswithin the cavity of the split gate valve;

FIG. 5 is an exploded perspective view of an embodiment of a body of thesplit gate valve and the pair of gate sections;

FIG. 6 is cross-sectional view of an embodiment of the body of the splitgate valve with the pair of gate sections inserted within the body,taken along line 6-6 of FIG. 5;

FIG. 7 is a perspective cutaway view of an embodiment of a ball screwfor use as the rolling actuator; and

FIG. 8 is a perspective cutaway view of an embodiment of a roller screwfor use as the rolling actuator.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Certain embodiments discussed below include a system and method thataddresses one or more of the above-mentioned inadequacies of aconventional large bore and/or high pressure gate valve. In certainembodiments, a system includes a split gate valve that includes a pairof gate sections (e.g., slab gates) coupled together and configured tomove together within a cavity of the split gate valve between an openposition and a closed position. The pair of gates sections allows thesplit gate valve to control flows of two different fluids with each gatesection. In addition, the two gates sections allow the isolation of afluid within a cavity of the split gate valve. The split gate valve alsoincludes a rolling actuator (e.g, ball screw or roller screw) configuredto receive a rotational input (e.g, from a drive) and to convert therotational input into linear motion to move the pair of gate sectionsbetween the open and closed positions. In some embodiments, the pair ofsplit gates sections includes a biasing mechanism (e.g., one or moresprings) to bias each gate section of the pair of the gate sections awayfrom each other to form a double seal in the split gate valve. Theformation of the double seal allows the filling of the cavity of thesplit gate valve to test each seal of the double seal at the same time.In certain embodiments, the split gate valve includes a body with anopening (e.g., generally rectangular) for the pair of gate sectionsconfigured for the insertion of the pair split gate sections and toclosely fit the gate sections to minimize deflection.

FIG. 1 illustrates an embodiment of a split gate valve 10 having arolling actuator 12. Typically, the split gate design limits the use ofthe split gate valve 10 to valves 10 with smaller bores (e.g., less thanapproximately 5 inches in diameter) and/or lower pressure ratings (e.g.,less than approximately 10,000 psi) due to the amount of force requiredto move the split gate in large bore and/or high pressure valves 10.However, the rolling actuator 12 enables the application of lessmechanical force or torque to the split gate valve 10 to open and closethe valve 10 (i.e., move the gate). Thus, the rolling actuator 12enables the use of the split gate design with large bore and/or highpressure valves 10 or any other combination of bore size and operatingpressure that would require the rolling actuator 12 to reduce the amountof mechanical force or torque needed to open and close the valve 10(e.g., a smaller bore size with high operating pressure or a larger boresize with a low operating pressure). The split gate valve 10 isgenerally configured to control a flow of fluid through the split gatevalve 10 in various applications. For example, the split gate valve 10may be employed in applications relating to oil and gas industries,power generation industries, petrochemical industries, and the like. Forexample, the split gate valve 10 may be coupled to a Christmas tree forpetroleum and natural gas extraction. In some embodiments, the splitgate valve 10 includes a large bore. For example, the bore of the splitgate valve 10 may be at least approximately 5 inches in diameter. Inother embodiments, the split gate valve 10 includes a smaller bore. Forexample, the bore of the split gate valve 10 may be less thanapproximately 5 inches. The diameter of the bore may range fromapproximately 3 to 20 inches, approximately 3 to 15 inches,approximately 3 to 10 inches, approximately 10 to 15 inches, orapproximately 15 to 20 inches. For example, the bore may beapproximately 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, 20 inches, or any other diameter therebetween. In other embodiments,the split gate valve 10 is configured to operate at a high pressure ofat least approximately 10,000 pounds per square inch (psi). In someembodiments, the split gate valve 10 is configured to operate atpressure lower than approximately 10,000 psi. For example, the splitgate valve 10 may operate at pressures ranging from approximately 5,000to 30,000 psi or more. For example, the split gate valve 10 may operateat pressures ranging from approximately 5,000 to 25,000 psi,approximately 10,000 to 20,000 psi, approximately 5,000 to 10,000 psi,approximately 10,000 to 15,000 psi, approximately 15,000 to 30,000 psi,approximately 15,000 to 25,000 psi, approximately 20,000 to 30,000 psi,approximately 20,000 to 25,000 psi, or approximately 25,000 to 30,000psi. In certain embodiments, the split gate valve 10 may include a bore(e.g., small bore size) of at least approximately 4 inches in diameterand be configured to operate at a pressure (e.g., high pressure) of atleast approximately 10,000 psi. In other embodiments, the split gatevalve 10 may include a bore (e.g., large bore size) of at leastapproximately 9 inches in diameter and be configured to operate at apressure (e.g., low pressure) of at least 5,000 psi.

In the illustrated embodiment, the split gate valve 10 includes anactuation system 14 including a drive 16 and the rolling actuator 12.The actuation system 14 is coupled to a body 18 of the split gate valve10. For example, the actuation system 14 may be coupled to a top portionof the body 18 via a bonnet 19. A bottom portion of the body 18 is alsocoupled to a bonnet 21. In certain embodiments, the split gate valve 10may not include the bonnet 21 attached to the bottom portion of the body18. Alternatively, split gate valve 10 may include a single body coupledto the actuation system 14. The body 18 may be constructed of cast iron,ductile iron, cast carbon steel, gun metal, stainless steel, alloysteels, corrosion resistant alloys, and/or forged steels. The split gatevalve 10 includes a gate 20 (e.g., split gate) that include a pair ofgate sections 22 and 24 disposed within a cavity 26 of the body 18,therein the gate sections 22 and 24 are configured to move between anopen position and a closed position. As illustrated, the gate 20 isdisposed in the closed position. In addition, as illustrated, each gatesection 22 and 24 includes a rectangular cross-sectional profile. Thebody 18 of the split gate valve 10 includes an inlet 28 and an outlet 30configured for a flow of a fluid through a bore 32 of the body 18 into apassage 34 of the split gate valve 10. In certain embodiments, theoutlet 30 may act as an inlet allowing fluid flow into the cavity 26from either side of the split gate valve 10. In some embodiments, theinlet 28 may act as an outlet and the outlet 30 may act as an inlet. Asmentioned above, in certain embodiments, the bore 32 may include adiameter 36 of at least approximately 5 inches. For example, thediameter of the bore 32 may range from approximately 5 to 20 inches,approximately 5 to 15 inches, or approximately 5 to 10 inches, orapproximately 10 to 15 inches. The passage 34 of the split gate valve 10includes a passage 38 (indicated by dashes lines) through the gate 20 toallow flow through the split gate valve 10 from the inlet 28 to theoutlet 30 when the gate 20 is in an open position (see FIGS. 2-4).

The split gate valve 10 is configured to open and close in response toan actuation force from the actuation system 14. In particular, thedrive 16 is configured to provide a rotational input (e.g., rotationalforce or torque) to the rolling actuator. The drive 16 may be a manualdrive or an automatic (e.g., powered) drive. For example, the drive 16may include a handle or wheel configured to be rotated by an operator.By further example, the drive 16 may include a motor, such as anelectric motor, a pneumatic motor, or a hydraulic motor. The rollingactuator 12 is configured to convert the rotational input received bythe drive 16 into a linear motion (e.g., linear activation force) tomove the gate 20 (i.e., the pair of gates sections 22 and 24) betweenopen and closed positions. In certain embodiments, the rolling actuator12 may include a ball screw or a rolling screw. The rolling actuator 12is configured to reduce the amount of friction to operate the stem valve10. In particular, the rolling actuator 12 reduces the amount of torqueor force required to move the gate 20 within the split gate valve 10.The rolling actuator 12 is coupled to a top portion 40 of the gate 20via a stem 42 (e.g., an operating stem) configured to facilitate themovement of the gate 20 between the open and closed positions. A bottomportion 44 of the gate 20 is also coupled to a stem 46 (e.g., abalancing stem). The stems 42 and 46 move along bores 45 and 47 ofbonnets 19 and 21, respectively. In certain embodiments, where the splitgate valve 18 includes a single body 18, the stems 42 and 46 may movealong bores of the single body 18. Each of the stems 42 and 46 may beconnected to both gate sections 22 and 24 via connectors. For example,both the top portions 40 and the bottom portions 44 of the gate sections22 and 24 may form cavities to surround a T-connecter (see FIG. 5)located at the end of each of the stems 42 and 46 near to the gate 20.

As mentioned above, the gate 20 includes the pair of gate sections 22and 24 (e.g., slab sections). The split gate arrangement of the gate 20includes advantages over a single gate arrangement. For example, twodifferent fluids on different sides of the split gate valve 10 may beseparated from each other by the pair of gate sections 22 and 24. Also,a fluid may be pumped into the cavity 26 of the split gate valve 10 forisolation. For example, the cavity 26 may be filled with a fluid (e.g.,liquid or gas) to further bias each gate section 22 and 24 away fromeach other to form seals. In addition, as mentioned above, fluid may bepumped into the cavity 26 from both sides of the split gate valve 10.Further, each gate section 22 and 24 may be constructed of a differentmaterial suitable for the fluid on its respective side of the split gatevalve 10. For example, the material may be corrosion resistant, wearresistant, and/or chemical resistant. The gates sections 22 and 24 maybe constructed of cast carbon steel, gun metal, stainless steel, alloysteels, corrosion resistant alloys, and/or forged steels. Also, asdiscussed in greater detail below, gate sections 22 and 24 form a doubleseal which allows the testing of each seal at the same time (i.e.,simultaneously).

As to the details of the split gate arrangement of the gate 20, the pairof gates sections 22 and 24 include a biasing mechanism 48 disposedbetween them. The biasing mechanism 48 is configured to bias the gatesections 22 and 24 away from each other in directions 50 and 52,respectively. Each gate section 22 and 24 is biased against a seat 54(e.g., annular seat) of the body 18 of the split gate valve 10 to form adouble seal (i.e., a seal on each side of the valve 10). The seat 54 maybe constructed of ceramic, cast iron, ductile iron, cast carbon steel,gun metal, stainless steel, alloy steels, corrosion resistant alloys,and/or forged steels. As illustrated, the biasing mechanism 48 includesa spring 56. In other embodiments, the biasing mechanism 48 may includea cam mechanism or an elastic material. The formation of a seal by eachgate section 22 and 24 allows seal testing for each gate face (i.e., theinlet 28 and outlet 30 sides) to occur at a valve rated working pressureduring the introduction of a test pressure into the cavity 26 of theseat valve 10.

The pair of gates sections 22 and 24 also includes a coupling mechanism58 to couple the gate sections 22 and 24 together. Due to the couplingmechanism 58, the gate sections 22 and 24 are configured to movetogether within the cavity 26 of the split gate valve 10 between theopen and closed positions. In particular, in response to a rotationalinput provided by the drive 16, the rolling actuator 12 converts therotational input into a linear motion that jointly moves the coupledgate sections 22 and 24 between the open and closed positions. Incertain embodiments, the coupling mechanism 58 may include a pinextending into slots with each gate section 22 and 24. The couplingmechanism 58 guides the movement of the gate sections 22 and 24 away andtoward one another. In particular, the coupling mechanism 58 guidesmovement of the gate sections 22 and 24 towards the seat 54 in responseto biasing force of biasing mechanism 48 (e.g., spring). The split gatevalve 10 as described above allows rolling friction (via the rollingactuator 12) to reduce the work required to mechanically operate thevalve 10, in particular, large bore and/or high pressure gate valves 10.

FIG. 2 illustrates an embodiment of the split gate valve 10 in an openposition. As illustrated, the passage 38 through the gate 20 (i.e., gatesections 22 and 24) is aligned with the bore 32 of the inlet 28 and theoutlet 30 to form the passage 34 through the split gate valve 10. Thesplit gate valve 10 is as described in FIG. 1 except for an added gearbox 68 in the actuation system 14. The gear box 68 is disposed betweenthe drive 16 and the rolling actuator 12. The gear box 68 is configuredto reduce the amount of rotational torque used to move the gate 20(i.e., gate sections 22 and 24) between the open and closed positions.For example, the gear box 68 may include internal gearing coupled to thedrive 16. For example, the internal gearing may include gear ratiosranging from 4:1 to 20:1. As described above, the rolling actuator 12converts the rotational input from the drive 16 and the gear box 68 intoa linear motion to move the pair of gates sections 22 and 24 betweenopen and closed positions. The split gate valve 10 as described allowsrolling friction (via the rolling actuator 12) to reduce the workrequired to mechanically operate the valve 10, in particular, large boreand/or high pressure gate valves 10.

FIGS. 3 and 4 illustrate embodiments of the actuation system 14 of thesplit gate valve 10. The split gate valve 10 is as described in FIG. 1except that the rolling actuator 12 is disposed within the cavity 26 ofthe split gate valve 10. The rolling actuator 12 may be disposed withinthe cavity 26 of the split gate valve 10 when the environment within thecavity 26 is suitable for the actuator 12. In embodiment of FIG. 3, therolling actuator 12 is disposed within the cavity 26 coupled to the stem42 (e.g., the operating stem) outside of the gate sections 22 and 24. Inthe embodiment of FIG. 4, the rolling actuator 12 is disposed within thecavity 26 coupled to the stem 42 between the gate sections 22 and 24. Inthe embodiments of both FIGS. 3 and 4, as above, the rolling actuator 12converts the rotational input from the drive 16 into a linear motion tomove the pair of gates sections 22 and 24 between open and closedpositions. The split gate valve 10 as described allows rolling friction(via the rolling actuator 12) to reduce the work required tomechanically operate the valve 10, in particular, large bore and/or highpressure gate valves 10.

FIG. 5 illustrates a perspective view of an embodiment of both the body18 and the gate sections 22 and 24 for the split gate valve 10. Asillustrated, the body 18 includes a cuboidal shape with a plurality offaces 78 (e.g., six). For example, the body 18 may be shaped as a rightcuboid, a rectangular box, a rectangular heaxahedron, a rightrectangular prism, square cuboid, square box, or right square prism.Alternatively, the body 18 may include a circular, oval, or oblongshape. As illustrated, the body 18 includes a pair of opposite faces 78(e.g., face 80) including large bores 32 for the passage of fluidthrough the split gate valve 10. In certain embodiments, the bore 32includes diameter 36 that may be at least approximately 5 inches indiameter. In some embodiments, the bore 32 includes diameter 36 that maybe less than approximately 5 inches. The diameter 36 may range fromapproximately 3 to 20 inches, approximately 3 to 15 inches, orapproximately 3 to 10 inches, or approximately 10 to 15 inches, orapproximately 15 to 20 inches. For example, the diameter 36 may be 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 inches, or anyother diameter therebetween.

In addition, the body 18 includes a pair of opposite faces 78 (e.g.,face 82) that each includes an opening 84 configured for the insertionof the pair of gate sections 22 and 24 along a length 86 of the gatesections 22 and 24. As illustrated, the opening 84 includes arectangular perimeter 88 with rounded corners 90. In other embodiments,the perimeter 88 of the opening 84 may be rectangular with right-angledcorners 90, square with rounded corners 90, or square with right-angledcorners 90. Alternatively, the perimeter 88 of the opening 84 may becircular, round, oval, or oblong. In particular, the perimeters 88 ofthe opening 84 and the cavity 26 of the body 18 are configured toclosely fit around the gate 20 when the gate 20 is inserted within thebody 18. Thus, cavity 26 of the body 18 is configured to allow the gate20 to consume nearly all of the space within the cavity 26. Inparticular, gate 20 engages substantially the entire cavity 26. Tightlyfitting the cavity 26 of the body 18 to the gate 20 allows the reductionin size of the body 18 (i.e., reduction in material) minimizing theamount of deflection experienced by the split gate valve 10 under loadpressure. In addition, using the generally rectangular opening 84 addsmore material between the gate 20 and the body 18 (e.g., thicker walls)to increase the strength and rigidity of the body 18 as opposed to acircular opening. In other words, the rectangular opening 84 allowsthicker walls surrounding the gate 20 that otherwise would be cut awaywith a circular opening. However, as mentioned above, the opening 84 maybe circular, round, oval, or oblong as long as the shape meets thedesign criteria for the split gate valve 10 such as fitting the gate 20and the seat 54.

The shape of the perimeter 88 of the opening 84 and the cavity 26depends on a cross-sectional area of the gate 20 along a width 92 of thegate 20. As illustrated, each gate section 22 and 24 includes a mainbody 94 with a generally rectangular shape along the length 86 of thesections 22 and 24. In addition, each gate section 22 and 24 includesends 96 and 98 and sides 100 and 102 that taper away from the main body94. In certain embodiments, each gate section 22 and 24 may include flatends 96 and 98 and flat sides 100 and 102. End 96 forms a cavity 99 tosurround a T-connector located at the end of the stem 42. End 98 alsoforms a cavity (not shown) to surround a connector (e.g., T-connector)located at the end of the stem 44. Further, each gate section 22 and 24includes an opening 104, defining passage 38 through the gate 20,configured to allow the flow of fluid through the gate 20 when the gate20 is aligned with the bore 32 of the body 18. In some embodiments, theopening 104 of each gate section 22 and 24 may include a diameter 106equivalent to the diameter 36 of the bore 32 of the body 18. In otherembodiments, the diameter 105 of the opening 104 of each gate section 22and 24 may be smaller than the diameter 36 of the bore 32 of the body18.

FIG. 6 illustrates the close fit between the body 18 and the gate 20upon insertion of the gate 20 into the body 18. In particular, FIG. 6 isa cross-sectional view of the body 18 disposed about the gate 20 takenalong line 6-6 of FIG. 5. The body 18 and the gate 20 are as describedin FIGS. 1 and 5. In particular, the gate sections 22 and 24 areinserted within the opening 84 into the cavity 26 of body 18 with thelength of 86 of the gate 20 crosswise (i.e. perpendicular) to the flowinto passage 34 through the inlet 28 and outlet 30 of the body 18. Theperimeter 88 of the cavity 26 and the opening 84 closely fit around bothgate sections 22 and 24, thus, the gate 20 takes up most of the spacewithin the cavity 26 of the body 18. In addition, as described above,the gate sections 22 and 24 include at least one biasing mechanism 48disposed between them to bias each gate section 22 and 24 away from eachother to form a double seal (e.g., seals 116 and 118) with the seat 54of the body 18.

As mentioned above, these embodiments of the body 18 and gate 20 areemployed with the actuation system 14 that includes the rolling actuator12 to reduce the work required to mechanically operate the valve 10 (viarolling friction), in particular, large bore and/or high pressure gatevalves 10. FIGS. 7 and 8 illustrate some, but not all, of theembodiments of the rolling actuator 12. FIG. 7 illustrates an embodimentof the rolling actuator 12 that includes a ball screw 128. Although FIG.7 illustrates one embodiment of the ball screw 128, the ball screw 128may include any type of ball screw mechanism. The ball screw 128 may bea part of or separate from the stem 42 (e.g., the operating stem) of thesplit gate valve 10. The illustrated ball screw 128 includes a screwshaft 130 including helical grooves 132 and a nut 134 including aplurality of ball bearings 136. The helical grooves 132 provide apathway for the ball bearings 136 to travel along as the nut 134receives a rotational input as indicated by arrow 138. The ball screw128 may include a recirculation mechanism to recirculate the ballbearings 136 into the helical grooves 132. The ball screw 128 isconfigured to convert the rotational input 138 into a linear motion asindicated by arrow 140, while minimizing friction to provide a highmechanical efficiency. The ball screw 128 may be constructed of chromesteel, stainless steel, and/or alloy steels. The ball bearings 136 maybe constructed of chrome steel, stainless steels, alloy steels, and/orceramic.

Alternatively, FIG. 8 illustrates the rolling actuator 12 including aroller screw 150. Although FIG. 8 illustrates one embodiment of theroller screw 150, the roller screw 150 may include any type of rollerscrew mechanism. For example, the roller screw 150 may include aplanetary roller screw, an inverted roller screw, a recirculating rollerscrew, or a bearing ring roller screw. The roller screw 150 may be partof or separate from the stem 42 (e.g., the operating stem) of the splitgate valve 10. The roller screw 150 includes a screw shaft 152 includinghelical grooves 154 and a nut 156 including a plurality of rollers 158disposed between opposite rings (e.g., ring 160). Each roller 158 may bethreaded (e.g., threads 162) or grooved. The helical grooves 154 providea pathway for the threaded or grooved rollers 158 to travel along as thenut 156 receives a rotational input as indicated by arrow 138. Theroller screw 150 is configured to convert the rotational input 138 intoa linear motion as indicated by arrow 140, while minimizing friction toprovide a high mechanical efficiency. The roller screw 150 may beconstructed of chrome steel, stainless steel, and/or alloy steels. Asmentioned above, the rolling actuator 12 (e.g., the ball screw 128 orthe roller screw 150) is configured to reduce friction and to covertrotational input (e.g., received by the drive 16) into linear motion tomove the pair of gate sections 22 and 24 between the open and closedpositions within the split gate valve 10. Thus, the rolling actuator 12reduces the work required to mechanically operate the split gate valve10, in particular, large bore and/or high pressure gate valves 10.

As discussed above, the disclosed embodiments include the split gatevalve 10 that includes the pair of gate sections 22 and 24 (e.g., slabgates) coupled together and configured to move together within thecavity 26 of the split gate valve 10 between open and closed positions.The split gate valve 10 includes the rolling actuator 12 to reduce theamount of mechanical force or torque required to move the split gatebetween the open and closed positions in large bore and/or high pressurevalves. In addition, the gate sections 22 and 24 form a double sealagainst the seat of 54 of the split gate valve 10. The pair of gatessections also allows the split gate valve 10 to control flows of twodifferent fluids with each gate section 22 and 24. In addition, thedouble seal allows the isolation of a fluid within the cavity 26 of thesplit gate valve 10. Further, the double seal allows testing of eachseal at the same time by filling the cavity of the split gate valve 10with a fluid. In certain embodiments, the body 18 of the split gatevalve 10 includes a rectangular opening configured to tightly fit thegate 20 allowing a reduction in size of the body 18, thus, minimizingthe amount of deflection experienced by the split gate valve 10 underload pressure.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

1. A system, comprising: a valve assembly, comprising: a valve bodyhaving a fluid passage that intersects with a valve cavity, wherein thevalve cavity has four flat interior sides extending along an axis of thevalve cavity, and an exterior of the valve body has four flat exteriorsides extending along the four flat interior sides; and a valve disposedin the valve cavity.
 2. The system of claim 1, wherein the exterior hasa substantially rectangular outer perimeter having the four flatexterior sides.
 3. The system of claim 1, wherein the valve cavity has asubstantially rectangular inner perimeter having the four flat interiorsides.
 4. The system of claim 1, wherein the four flat interior sidesare substantially parallel with the respective four flat exterior sides.5. The system of claim 1, wherein the valve body has a substantiallyuniform wall thickness between the four flat interior sides and therespective four flat exterior sides.
 6. The system of claim 1, whereinthe four flat exterior sides comprise first and second flat exteriorsides that are opposite from one another and substantially parallel toone another.
 7. The system of claim 6, wherein the four flat exteriorsides comprise third and fourth flat exterior sides that are oppositefrom one another and generally crosswise to the first and second flatexterior sides.
 8. The system of claim 7, wherein the third and fourthflat exterior sides are substantially parallel to one another.
 9. Thesystem of claim 1, wherein the four flat interior sides comprise firstand second flat interior sides that are opposite from one another andsubstantially parallel to one another.
 10. The system of claim 9,wherein the four flat interior sides comprise third and fourth flatinterior sides that are opposite from one another and generallycrosswise to the first and second flat interior sides.
 11. The system ofclaim 10, wherein the third and fourth flat interior sides aresubstantially parallel to one another.
 12. The system of claim 1,wherein the four flat exterior sides comprise first and second flatexterior sides that are opposite from one another, the four flatinterior sides comprise first and second flat interior sides that areopposite from one another, the first flat exterior side is substantiallyparallel to the first flat interior side, and the second flat exteriorside is substantially parallel to the second flat interior side.
 13. Thesystem of claim 12, wherein the four flat exterior sides comprise thirdand fourth flat exterior sides that are opposite from one another, thefour flat interior sides comprise third and fourth flat interior sidesthat are opposite from one another, the third flat exterior side issubstantially parallel to the third flat interior side, and the fourthflat exterior side is substantially parallel to the fourth flat interiorside.
 14. The system of claim 1, where the valve has four sides incontact with the respective four flat interior sides of the valvecavity.
 15. The system of claim 1, wherein the valve comprises a gatevalve.
 16. The system of claim 15, wherein the gate valve is split intofirst and second valve sections.
 17. The system of claim 16, comprisinga biasing element between the first and second valve sections.
 18. Thesystem of claim 1, comprising a rolling actuator coupled to the valve.19. The system of claim 1, wherein the valve assembly is coupled to acomponent of a mineral extraction system configured to extract petroleumor natural gas.
 20. A system, comprising: a valve body having a fluidpassage that intersects with a valve cavity, wherein the valve cavityhas four flat interior sides extending along an axis of the valvecavity, and an exterior of the valve body has four flat exterior sidesextending along the four flat interior sides.
 21. The system of claim20, comprising a valve assembly having a valve disposed in the valvecavity.
 22. The system of claim 20, wherein the exterior has asubstantially rectangular outer perimeter having the four flat exteriorsides, and the valve cavity has a substantially rectangular innerperimeter having the four flat interior sides.
 23. The system of claim22, wherein the substantially rectangular outer perimeter issubstantially parallel with the substantially rectangular innerperimeter.
 24. A method, comprising: forming a valve body having a fluidpassage that intersects with a valve cavity, wherein the valve cavityhas four flat interior sides extending along an axis of the valvecavity, and an exterior of the valve body has four flat exterior sidesextending along the four flat interior sides.
 25. The method of claim24, comprising installing a valve in the valve cavity, wherein the valvecomprises four flat sides in contact with the respective four flatinterior sides of the valve cavity.